Well let's see shall we, we'll break it down:
Combat gains don't matter. The entire point of the challenge rating system is that monsters of equal challenge pose roughly equivalent threats. That's not me dismissing anything, that's me acknowledging what the system is for.
Darkvision or Blindsight don't matter unless the beast can communicate with you. "You enter the vault when suddenly the door slams closed, trapping you in darkness." "I summon [beast with blindsight]. What do I see?" "The [beast with blindsight] looks around, unnerved at being trapped." No information gained. At best it might react audibly to a threat it can detect.
Let's say you want to track a scent. You have a sample of the scent to start with? You'll need one. You sure your target went by land? They'll need to off. Etc.
As for carry capacity. I scoff, scoff at that. Unless you're within one hour of civilisation, using Conjure Animals to carry stuff just delays the problem by the hour, or until your concentration breaks. Whereas you can just hire hirelings to carry stuff for you. It costs, what, 1gp/day?
i would suggest you look beyond a few cases where you can skew these as useless traits and be a little more creative with what kinds of solutions you see this spell offering up for what kinds of problems.
Really, it may be an eye opener.
Then again, maybe not, really does depend on your games and the kinds of situations that come up and how few they are.